Automatic excess-heat fuse for electric machines and apparatus



w. r-lillcKEL E1' AL AUTOMATIC EXCES'S HEAT FUSE FOR ELECTRIC MACHINES AND APPARATUS Amm nl [n van 075:

Patented lltec. 15, 1925.

UNITED STATES rATENT certes.

WILLIAM HICKEL, OF ZURCl-L AND OTTO PLETSCHER, JR., OF LBTSREDEN, SVITZERLAND.

AUTOMATIC EXCESS-THAT FUSE FOB ELECTRIC BIACHINES AND APPARATUS.

Application filed August 11, 1923. Serial No. 656,835.

To @ZZ whom 'it may concern:

Be it known that we, VILLIAM HIoxnL, a resident of Zurich, Switzerland, and OTTO PLnTsoHnn, Jr., a resident of Albisrieden, in the Canton of Zurich, Switzerland,citizens of the Republic of Switzerland, have invented an Automatic Exess-Heat Fuse for Electric Machines and Apparatus, of which the following is a specification.

Our invention is based upon the idea that a fuse strip inserted in the circuit is melted by the temperature of the excess heat of the surroundings and expelled in this condition into an insulating chamber, the current being interrupted thereby and the melted mass contained in the insulating` chamber prevented from getting into touch with the contacts in order to avoid the formation of sparks or electric arcs.

An embodiment of our invention is illustrated by way of example in the accompanying drawing, in which Fig. 1 is an internal view of the excess heat fuse, the fuse pin being inserted therein;

Fig. 2 a section on line A A of Fig. 1;

Fig. 3 an incomplete internal view, the fuse pin having been melted and expelled;

Fig. 4L a section on line B-B of Fig. 3;

Fig. 5 a partial section on line C-C of Fig. 1;

g. 6 a partial section on line D--D of .1; g. 7 a view of the inside of cover;

Fig. 8 a side view thereof, and

Fig. 9 a section on line lil-E of Fig. 7.

A easing 1 made of insulating` material carries a central piece 13 with an opening 14, in which an expeller and spark extinguisher 5 made of non-combustible insulating material and provided with a stop is movably arranged. This expeller and spark extinguisher is subjected to the action of a spiral spring 6 which presses it against the fuse pin 9 as shown in Fig. 1, the two metallic contact pieces 8 being electrically connected with each other on the cover 7 by said pin.

On either side of the central piece 13 of the casing there are provided in the chambers 20 the junction contact pieces 2 made of some material conducting curr-ent and heat, such as copper, brass or the like, the conductors e being connected thereto and Fi Fig.

clamped in the openings 18 of casing 1 by 55 means of screws The bottom surfaces of the connecting contact pieces 8, fixed to cover 7, come to rest upon the top surfaces of the shoulder of the junction contact pieces 2, whereby two contacts are electrically connected with each other on either side. i

In each of the two insulating chambers 20 a window opening 15 is provided enabling the heat rays from the heated-up supce port to pass through and to act upon the bottom surfaces of the junction contact pieces 2 which absorb said rays.

Now, should such a heating-up take place as to be prejudicial to the current conducting parts of the electric machine or apparatus to be protected, the contact pieces 2 and 8 are heated up by the heat which enters through the window openings 15, to

such a degree that the fuse pin 9, adapted to melt at a certain temperature, melts and interrupts the circuit when said temperature is exceeded. As may be seen from Figs. 3 and 4l, the melted portion of the fuse pin 9 is expelled into the insulating chamber 12 80 by the expeller and spark extinguisher 5, thus enabling the latter to close up, by its thicker portion acting as a stop, the interval 19, delimited by lug 16 of casing 1 and by lug 17 of cover 7 as well as by the central 85 piece 13 and the contacts, in such a manner that the melted parts of the fuse pin 9 can no longer come into contact with current conducting parts.

lThe cover 7 secured to casing 1 by the 90 screws 11 is so formed as to it readily into said casing, thus enabling the surfaces of the contact pieces 8 and those of the junc-V tion contact pieces 2 to come to rest upon each other so as to lit exactly before the cover itself can get home.

When a 'fuse pin is melted, the cover 7 is simply unscrewed, the screws 10 released and the two ends of the fuse pin 9 removed from the contacts 8, whereupon a new pin 10o Having fully described our invention,

what we claim as new, and desire to secure by Letters Patent, 1s:-

l. An automatic excess heat fuse for electric machines and apparatus, comprising a casing of insulating material, a snugly fitting lid connected detachably to said casing, two spaced contact pieces secured to said casing, spaced contact pieces connected to the lid so as to bear against the contact pieces of the casing, a fuse pin carried by the contact pieces of the lid so as to bridge the gap between them, and a spring-pressed plunger of non-combustible insulating material held by the casing so as to bear normally against the fuse pin and so as to be interposed between the pin holders when the fuse burns out.

2. An automatic excess heat fuse for electric machines and apparatus, comprising a casing of insulating material having a pair of spaced windows, a snugly iitting lid connected detachably to said casing, a pair of spaced, shouldered contact pieces secured to said casing so as to cover the windows, a pair of spaced contact pieces connected to said lid so as to bear against the contact pieces of the casing beside the shoulders of the same, a fuse pin held by the contact pieces of the lid so as to bridge the gap between them, and a spring-pressed plunger of non-combustible insulating material held by the casing between the contact pieces of the latter, said plunger being arranged so as to rest normally on the fuse pin and so as to be interposed between the pin holders when the fuse burns out.

VILLIAM HICKEL. OTTO PLETSCl-IER,JR. 

